Gripping device

ABSTRACT

A gripping device, which is a part of a rock drill, is arranged to grip a drill string. It has a housing in which a number of gripping jaws are disposed around the drill string. In the housing but outside the jaws, a sleeve is clamped as a seal so that a pressure chamber is formed between the sleeve and the housing. When the pressure chamber is pressurized, the sleeve forces the jaws to grip the drill string.

United States Patent Inventors Nils Gunnar Jonson Jakobsberg; John Arne Lagerstedt, Skarholmen, Sweden Appl. No. 859,153 Filed Sept. 18, 1969 Patented Feb. 23, 1971 Assignee Atlas Copco Alttiebolag Nacka, Sweden Priority Oct. 4, 1968 Sweden 13475/68 GRIPPING DEVICE 8 Claims, 5 Drawing Figs.

US. Cl. 173/152, 173/149 Int. E2lc 5/00,

501 FieldofSearch 173/149, 152, 140; 214/338; 175/122 56] References Cited UNITED STATES PATENTS 2,730,331 l/l956 Harinck 173/149 3,212,591 10/1965 Tucker 173/149 Primary Examiner-James A. Leppink Attorney-Eric Y. Munson ABSTRACT: A gripping device, which is a part of a rock drill, is arranged to grip a drill string. It has a housing in which a number of gripping jaws are disposed around the drill string. In the housing but outside the jaws, a sleeve is clamped as a seal so that a pressure chamber is formed between the sleeve and the housing. When the pressure chamber is pressurized, the sleeve forces the jaws to grip the drill string.

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-- sum 1 or 3 NILS GUNNAR JONSSON and JOHN ARNE LAGERSTEDT INVENTORS BY ERIC Y MUNSON,

' Attprney PATENTE I J FEB23|97I 3565387 I SHEET 2 [IF 3 Fig4 NILS GUNNAR JONSSON and JOHN ARNE LAGERSTEDT INVENTORS BY ERIC Y. MUNSON, Attorney PATENTEU FEB23 197p 7 sum 3 OF 3 JONSSON and NILS GUNNAR JOHN ARNE LAGERSTEDT INVENTOR. S

BY ERIC Y MUNSON Attorney GRIPPING DEVICE This invention relates to a pressure fluid actuated gripping device which is a part of a rock or earth drilling apparatus for rotary drilling. The gripping device is arranged so as to grip a drill string for transmitting rotation or axial movement to the drill string. It has a rotatable housing in which gripping jaws are disposed around the drill string.

In connection with a prior embodiment of such a gripping device, there are utilized four pressure fluid actuated pistons working in cylinders to press the gripping jaws into firm engagement with the drill string. The cylinders are perpendicular to the drill string. In order to getsufficient gripping forces the hydraulic cylinders must be made so large that the gripping device become cumbersome. Besides, some oil leakage cannot be avoided when pistons are used which are slidable in cylin' ders. The leakage oil reduces the friction between the gripping jaws and the drill string. 7

It is a purpose-of the invention-'tojeliminate these disadvantages and to create a gripping device of the aforementioned type which is small and inexpensive.

' For these and other purposes, I provide a pressiire fluid actuated gripping device arranged as a part of a rock drilling apparatus for rotary drilling and comprising a rotatably mounted housinghaving annular end parts for permitting the introduction of a drill string longitudinally through the housing, an

elastomeric sleevelike piston element disposed in said housingto separate as a seal a pressure chamber between the housing and the piston element from a central space in the housing, and gripping jaws for gripping a drill string disposed around the drill string in said central space, said piston element being arranged to press the gripping jaws into firm engagement with the drill string when pressure fluid chamber.

The above and other objects of the invention are obvious.

from the following description nd and the accompanying drawings in which an embodiment of the invention is described by way of example. It is to be understood that various modifications may be made within the scope of the claims.

In the drawings: FIG. 1 is a side view, partly in section, of a vertically arranged rock and earth drilling apparatus of which a gripping device according to the invention is an essential part; FIG. 2 is a transverse section taken substantially along the line 2-2 in FIG. 1, some details of a feed bar being omitted; FIG. 3 shows some details of FIG. 2 on a larger scale; FIG. 4 is a section on a larger scale taken substantially along the line 4-4 in FIG. l, the gripping device, however, is shown in a section on the line 4-4 in FIG. 2; and FIG. 5 is a transverse section of a somewhat modified gripping device.

The rock drilling apparatus 10, illustrated in the FIGS., has a feed bar 11 which is supported by expanding units 12. Alternatively, the feed bar 11 may be carried by a wheeled substructure or be supported in another suitable way. A slide 13, which carries a drill 14, is slidabl'e along the feed bar 11 by means of two parallel chains 15, a chain 16, and a double-acting feed motor 17 in the form of a cylinder with a piston. The feed motor 17 has two supply conduits 17a for pressure fluid. A drill holder 18 of the vice-type is disposed at the forward portion of the feed bar 11. During drilling, the drill holder 18 guides a drill string, illustrated as a jointed drill pipe 19, but, for example during the making and breaking of joints, it holds the drill pipe 19 so as to prevent rotation and axial movement. A diamond drill bit 20 is screwed to the forward end of the drill rod 19, and flush water is supplied through a swivel 47 which is screwed to the rear end of the drill pipe. A chuck (gripping device) ,21 according to the invention is a part of the drill 14 which in FIG. 4 is shown in a longitudinal section. The chuck 21 has a housing 22 which is rotatably joumaled in the housing 23 of the drill 14 by means of a roller bearing 24 and a ball bearing 25. A cover 37 is a detachable end part of the chuck housing 22. Pressure fluid, preferably pressure oil, is supplied through a hose 26 and an annular groove 27 in the housing 23 into a passage 28 in the housing 22 of the chuck 21. Oil is permitted to leak through an annular clearance gap 29 between the nonrotating housing 23 of the drill 14 and the is supplied to said pressure rotating housing 22 of the chuck 21. The clearance gap 29 has preferably a width of 0.01-0.05 mm. The leakage oil is collected and conveyed back to a sump by means of a hose 30. Sealing rings 31 are arranged to seal against the oil which has passed the clearance gap 29 and, therefore, has only atmospheric pressure.

A reversible hydraulically operated rotary motor 46 is arranged to rotate the housing 22 of the chuck over a gearing which has gears 32, 33. The gear 32 is attached to the output shaft of the motor 46 by means of a key 35, and the gear 33 is attached to a projecting part of the housing 22 of the chuck 21 by means of another key 35. A sleevelike piston element 35 made of an elastomer, e.g. rubber, has flanges 36 which are clamped against the housing 22 of the chuck 21 by means of an end cover 37 of the housing 22 and a circular spacer sleeve 38 which has holes 39. Thus, the piston element 35 separates a pressure chamber 40, which is in communication with the passage 28, from a central space 41 through which the drill pipe 19 can be inserted as illustrated. Gripping jaws 42 are disposed in this central space 41 to grip the drill pipe 19 when the piston element 35 is loaded by means of pressure fluid in the pressure chamber 40. Guiding pins 43 are attached to the housing 22 and to the end cover 37 of the housing and arranged so as to guide the gripping jaws 42 in their radial move ment. When the chuck 21 is rotated, the guiding pins 43 transmit torque directly from the housing 22 'of the chuck to the gripping jaws 42, and the piston element 35 is not subject to torque.

Springs in form of spring plates 45 are fastened between axial grooves 44 in adjacent jaws 42 so as to bias the jaws into a nongripping position. The spring plates 45 and the gripping jaws'42 constitute a cylinder which supports the piston element 35 when the piston element is loaded by pressure fluid supplied through the hose 26. The pressure applied by the piston element 35 to the spring plates 45 is transmitted to the gripping jaws 42, which increases the gripping forces.

Suitably, the gripping jaws 42 have beveled outer edges 48, as illustrated in FIG. 3, so that the transition areas between the springs 45 and the gripping jaws 42 are smooth. Thus, there are no sharp edges or corners wearing down the piston element, and the whole interior surface of the piston element 35 is supported when the gripping jaws are in gripping position. The oil pressure upon the piston element 35 is illustrated by means of arrows in FIG. 3. I

Since the entire piston element 35 is supported and does not transmit any torque, it need not be reinforced. Therefore, it is inexpensive and easy to make.

In the modified chuck illustrated in FIG. 5, the details which correspond with details in the preceding FIGS. have been given the same reference numerals as in these FIGS. The springs 45 are in this chuck of the coil type, and the gripping jaws 42 exclusively constitute a cylinder for supporting the piston element 35, which is of the same type as in the preceding FIGS.

It is to be understood that the gripping device may be modified in various other ways within the scope of the claims.

We claim:

1. A pressure fluid actuated gripping device arranged as a part of a rock drilling apparatus for rotary drilling and comprising a rotatably mounted housing having annular end parts for permitting the introduction of a drill string longitudinally through the housing, an elastomeric sleevelike piston element disposed in said housing to separate as a seal a pressure chamber between the housing-and the piston element from a central space in the housing, and gripping jaws for gripping a drill string disposed around the drill string in said central space, said piston element being arranged to press the gripping jaws into firm engagement with the drill string when pressure fluid is supplied to said pressure chamber.

2. A gripping device according to claim 1 in which the housing is rotatable by means of a motor, and said gripping jaws are guided by means of guiding elements which are fixed to the housing and arranged to transmit torque from the housing to the gripping jaws when the housing is rotated.

3. A gripping device according to claim 2 in which said guiding elements are guiding pins, which are attached to the housing and parallel with the longitudinal axis of the housing.

4. A gripping device according to claim 3 in which springs are arranged to hold the gripping jaws in a nongripping position when said pressure chamber is relieved of pressure.

5. A gripping device according to claim 1 in which the gripping jaws are integral elements of a cylinder which is arranged to support substantially the whole interior surface of the sleevelike piston element when said pressure chamber is pressurized.

6. A gripping device according to claim 4 in which said springs are spring plates, each of which is fastened between two adjacent gripping jaws, said spring plates and the gripping jaws constituting a cylinder which is arranged to support substantially the whole interior surface of the sleevelike piston element when said pressure chamber is pressurized.

7, A gripping device according to claim 1 in which the piston element has annular flanges, each of which is clamped between either of the end parts of the housing and a spacer sleeve disposed between said flanges.

8. A drilling apparatus arranged for rotary drilling in rock and comprising a feed bar, a drill slidably carried by said feed bar, and a feed motor for moving said drill axially with said feed bar, said drill comprising a drill housing, a chuck housing rotatably journaled in said drill housing, said drill housing and said chuck housing having a longitudinal hole through which a drill string can be introduced, a motor for rotating said chuck housing, an elastomeric sleevelike piston element disposed in said housing to separate as a seal a pressure chamber between the housing and the piston element from a central space in the housing, and gripping jaws for gripping a drill string disposed around the drill string in said central space, said piston element being arranged to press the gripping jaws into firm engagement with the drill string when pressure fluid is supplied to said pressure chamber. 

1. A pressure fluid actuated gripping device arranged as a part of a rock drilling apparatus for rotary drilling and comprising a rotatably mounted housing having annular end parts for permitting the introduction of a drill string longitudinally through the housing, an elastomeric sleevelike piston element disposed in said housing to separate as a seal a pressure chamber between the housing and the piston element from a central space in the housing, and gripping jaws for gripping a drill string disposed around the drill string in said central space, said piston element being arranged to press the gripping jaws into firm engagement with the drill string when pressure fluid is supplied to said pressure chamber.
 2. A gripping device according to claim 1 in which the housing is rotatable by means of a motor, and said gripping jaws are guided by means of guiding elements which are fixed to the housing and arranged to transmit torque from the housing to the gripping jaws when the housing is rotated.
 3. A gripping device according to claim 2 in which said guiding elements are guiding pins, which are attached to the housing and parallel with the longitudinal axis of the housing.
 4. A gripping device according to claim 3 in which springs are arranged to hold the gripping jaws in a nongripping position when said pressure chamber is relieved of pressure.
 5. A gripping device according to claim 1 in which the gripping jaws are integral elements of a cylinder which is arranged to support substantially the whole interior surface of the sleevelike piston element when said pressure chamber is pressurized.
 6. A gripping device according to claim 4 in which said springs are spring plates, each of which is fastened between two adjacent gripping jaws, said spring plates and the gripping jaws constituting a cylinder which is arranged to support substantially the whole interior surface of the sleevelike piston element when said pressure chamber is pressurized.
 7. A gripping device according to claim 1 in which the piston element has annular flanges, each of which is clamped between either of the end parts of the housing and a spacer sleeve disposed between said flanges.
 8. A drilling apparatus arranged for rotary drilling in rock and comprising a feed bar, a drill slidably carried by said feed bar, and a feed motor for moving said drill axially with said feed bar, said drill comprising a drill housing, a chuck housing rotatably journaled in said drill housing, said drill housing and said chuck housing having a longitudinal hole through which a drill string can be introduced, a motor for rotating said chuck housing, an elastomeric sleevelike piston element disposed in said housing to separate as a seal a pressure chamber between the housing and the piston element from a central space in the housing, and gripping jaws for gripping a drill string disposed around the drill string in said central space, said piston element being arranged to press the gripping jaws into firm engagement with the drill string when pressure fluid is supplied to said pressure chamber. 